Linking gene expression to productivity to unravel long- and short-term responses of seagrasses exposed to CO2 in volcanic vents

Irene Olivé,Miriam Ruocco,Rui Santos,Monya M Costa,Gabriele Procaccini,João Silva,Chiara Lauritano

doi:10.1038/srep42278

Irene Olivé, Miriam Ruocco + Show 5 more

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https://doi.org/10.1038/srep42278

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Abstract

Ocean acidification is a major threat for marine life but seagrasses are expected to benefit from high CO2. In situ (long-term) and transplanted (short-term) plant incubations of the seagrass Cymodocea nodosa were performed near and away the influence of volcanic CO2 vents at Vulcano Island to test the hypothesis of beneficial effects of CO2 on plant productivity. We relate, for the first time, the expression of photosynthetic, antioxidant and metal detoxification-related genes to net plant productivity (NPP). Results revealed a consistent pattern between gene expression and productivity indicating water origin as the main source of variability. However, the hypothesised beneficial effect of high CO2 around vents was not supported. We observed a consistent long- and short-term pattern of gene down-regulation and 2.5-fold NPP decrease in plants incubated in water from the vents and a generalized up-regulation and NPP increase in plants from the vent site incubated with water from the Reference site. Contrastingly, NPP of specimens experimentally exposed to a CO2 range significantly correlated with CO2 availability. The down-regulation of metal-related genes in C. nodosa leaves exposed to water from the venting site suggests that other factors than heavy metals, may be at play at Vulcano confounding the CO2 effects.

Highlights

Ocean acidification is a major threat for marine life but seagrasses are expected to benefit from high CO2
Our results showed that both the net plant productivity (NPP) and the gene expression of C. nodosa were significantly lower in plants incubated in CO2–rich water from Vulcano CO2 vents when compared to Reference water
Plants living in the venting site showed a general reduction in the expression of genes involved in various metabolic processes, those related with the light-dependent reactions of photosynthesis, carbon fixation and metabolic carbon assimilation when compared to plants from the Reference site

Summary

Introduction

Ocean acidification is a major threat for marine life but seagrasses are expected to benefit from high CO2. Experimental evidence for increased seagrass productivity as a response to elevated CO2 levels and ocean acidification is inconclusive, and scarce over long-time scale. The modulation of gene expression plays a central role in plant plasticity and adaptation to environmental changes[9], since physiological machinery and metabolic pathways are coordinated at the genetic level by an array of regulatory genes, which are affected by environmental stimuli[10]. Molecular techniques for studying gene expression have been increasingly recognized as a powerful tool for physiological research to assess the acclimation responses and adaptive potential of marine organisms to ocean acidification Gene expression can be used to assess the role that plasticity and long-term adaptation to high CO2 play in altering specific metabolic pathways related with the physiological response, and the fast acclimation www.nature.com/scientificreports/. The analysis of the expression levels of targeted genes may provide new understanding of molecular changes that accompany alterations in physiological states[13,14]

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